Field
This disclosure relates generally to drug delivery devices, and, more particularly, to delivering of a drug through a needle-based drug delivery device.
Background
An autoinjector is a medical device designed to deliver one or more doses of a particular drug in a manner that facilitates self-administration of the drug via a syringe needle. Autoinjectors were originally designed for military use to counteract nerve-agent poisonings. The devices later moved into the civilian realm, with the first civilian devices being introduced in the mid to late 1970s, to dispense epinephrine to treat anaphylaxis. More recently, these devices have seen broadened use.
By design, autoinjectors are easy to use and are intended for administration by patients to themselves, or by untrained personnel. Thus, they are typically self-contained and designed to require only a few basic steps to operate.
Typically, autoinjectors are spring actuated. This means that one or more springs are used to drive the drug through the needle of the autoinjector, and in some cases, to insert the needle into the patient as well. At least one spring is used to apply a force to the stopper of a syringe or cartridge, much in the manner that a person would manually actuate a syringe plunger, and drive the drug out of the syringe into the injection site. These autoinjectors typically deliver a full dose of their drug in about 5 to 10 seconds.
An alternative form of autoinjector is the gas jet injector, which dispenses with a needle entirely; instead using a high-pressure narrow jet of the drug itself to penetrate the skin. Gas jet injectors have predominantly been used for mass vaccinations, not single dose delivery, and involve delivery of the drug at pressures of about 4,000 psi almost instantaneously. Newer gas jet injectors use slightly lower pressures. In general however, gas jet injectors are limited in volume they can deliver in a single “shot” and the depth to which they can deliver the drug. In addition, as explosive/high impact technologies, they cause impact and jarring that can be problematic.
Current designs involve making tradeoffs among various controllable and uncontrollable factors to insure reliable, proper and complete dose delivery. However, the selected tradeoffs that provide for reliable, proper and complete dose delivery can result in the inability to provide certain desirable feature(s) or requiring of greater complexity to provide less than desirable version(s) of such feature(s).